Analysis on A Synoptic Process of Freezing Rain in Anshan City

Based on MICAPS(Meteorological Information Combine Analysis and Process System) and observational data in Anshan Observatory,the freezing rain event occurred rarely in Anshan on February 24 in 2010 was analyzed.The results showed that there existed the inversion layer from the ground to 850 hpa level even to 700 hPa level when the local surface temperature was below 0 ℃.The temperature stratification structure of coldness-warmth-coldness was prevailing from the upper level to the ground with the existence of the ice melting layer of a certain thickness.Thus the freezing event occurred in Anshan.

Predecessor Rain Events in the Yangtze River Delta Region Associated with South China Sea and Northwest Pacific Ocean(SCS-WNPO)Tropical Cyclones

Predecessor rain events(PREs) in the Yangtze River Delta(YRD) region associated with the South China Sea and Northwest Pacific Ocean(SCS-WNPO) tropical cyclones(TCs) are investigated during the period from 2010 to 2019.Results indicate that approximately 10% of TCs making landfall in China produce PREs over the YRD region;however,they are seldom forecasted. PREs often occur over the YRD region when TCs begin to be active in the SCS-WNPO with westward paths, whilst the cold air is still existing or beginning to be present. PREs are more likely to peak in June and September. The distances between the PRE centers and the parent TC range from 900 to 1700 km. The median value of rain amounts and the median lifetime of PREs is approximately 200 mm and 24 h, respectively. Composite results suggest that PREs form in the equatorward jet-entrance region of the upper-level westerly jet(WJ), where a 925-hPa equivalent potential temperature ridge is located east of a 500-hPa trough. Deep moisture is transported from the TC vicinity to the remote PREs region. The ascent of this deep moist air in front of the 500-hPa trough and frontogenesis beneath the equatorward entrance region of the WJ is advantageous for the occurrence of PREs in the YRD region. The upper-level WJ may be affected by the subtropical high and westerly trough in the Northwest Pacific Ocean, and the occurrence of PREs may favor the maintenance of the upper-level WJ. The upper-level outflow of TCs in the SCS plays a secondary role.

Genetic Analysis of a Heavy Rainstorm on June 29,2006 in Henan Province

Based on conventional radiosonde data, surface encrypted observation data and so forth, the diagnostic analysis of a heavy rainstorm in the central and east of Henan Province on June 29, 2006 was carried out from the aspects of its large-scale background, environmental field and physical characteristics. The results showed that under the effect of a favorable large-scale environmental field, the rainstorm was caused by a mesoscale system. The high-east and low-west circulation pattern, the eastward movement of high-level low trough, low-level shear lines and strengthening of low-level jet streams directly resulted in the occurrence of the heavy rainstorm.

Causes of Strong Sandstorm Weather on March 15,2021 in Ulanqab City

The severe sandstorm process in Ulanqab,Inner Mongolia on March 15,2021 was analyzed and discussed from the aspects of weather facts,weather causes and dynamic diagnosis.The results show that the strong cold air in West Siberia rapidly moved eastward,and the surface cold front moved eastward to Ulanqab with significant warming in the previous period,resulting in gale and sandstorm weather.This severe sandstorm process occurred in basically stable atmospheric stratification.During the strong sandstorm and extremely strong sandstorm process on March 15,the strong warming in the early period near the surface led to the surface thermal instability,and sand was generated by the upward movement of the Mongolian cyclone.Over the upper northwest air stream,barocline disturbance developed unsteadily,and the upper cold advection stimulated the secondary circulation of front perpendicular to the surface;the surface cyclone turned into strong cold front,and then strong sandstorm weather occurred in Ulanqab.

Analysis of a Local Rainstorm in Central Inner Mongolia

Based on conventional observation data,satellite cloud image data and new generation Doppler radar data,the local rainstorm weather situation and physical quantities in Ulanqab City from 08:00 to 20:00 on June 24,2019 were analyzed by means of synoptic methods.The results show that the local rainstorm was caused by the forward trough system and the convergence of warm and cold air,and triggered by the low-level jet and the surface convergence line.The splitting and merging of cloud clusters in satellite cloud images and strong radar echoes had a good guiding effect on short-term heavy precipitation.

Interdecadal Variations of Precipitation and Temperature in China Around the Abrupt Change of Atmospheric Circulation in 1976

The interdecadal characteristics of rainfall and temperature in China before and after the abrupt change of the general circulation in 1976 are analyzed using the global 2.5°×2.5° monthly mean reanalysis data from the National Centers for Environmental Prediction of US and the precipitation and temperature data at the 743 stations of China from the National Climate Center of China. The results show that after 1976, springtime precipitation and temperature were anomalously enhanced and reduced respectively in South China, while the reverse was true in the western Yangtze River basin. In summer, precipitation was anomalously less in South China, more in the Yangtze River basin, less again in North China and more again in Northeast China, showing a distribution pattern alternating with negative and positive anomalies （＂ , ＋, -, ＋＂）. Meanwhile, temperature shows a distribution of warming in South China, cooling in the Yangtze and Huaihe River basins, and warming again in northern China. In autumn, precipitation tended to decrease and temperature tended to increase in in South China and warming was most parts of the country. In winter, the trend across all parts of China. precipitation increased moderately The interdecadal decline of mean temperature in spring and summer in China was mainly due to the daily maximum temperature variation, while the interdecadal increase was mainly the result of the minimum temperature change. The overall warming in autumn （winter） was mostly influenced by the minimum （maximum） temperature variation. These changes were closely related to the north-south shifts of the ascending and descending branches of the Hadley cell, the strengthening and north-south progression of the westerly jet stream, and the atmospheric stratification and water vapor transport conditions.